Conventionally, a technique has been proposed which identifies the position of an object that got lost (hereinafter, referred to as a “search object”) by adopting RFID (Radio Frequency IDentification). For example, Patent Literature 1 describes a technique which reads an RF tag with a reader, performs radar capturing, and identifies the position of an object with the RF tag attached thereto, thereby searching the search object.
Further, as a technique for identifying the position of a moving object, a technique using a GPS (Global Positioning System) is known. Furthermore, PDR (Pedestrian Dead Reckoning) is known as a technique that can identify the position of a moving body even in an environment where receiving a GPS signal is difficult, for example, in doors. Patent Literature 2 describes a technique that identifies the position of a pedestrian by using the PDR technique, for example. Therefore, it can be considered to make the search object carry a portable terminal device having a PDR function therewith so that the position of the search object is transmitted to a monitor device for the search object.
Patent Literature 1: Japanese Patent Application Laid-open No. 2009-014646
Patent Literature 2: Japanese Patent Application Laid-open No. 2012-145457